An intraluminary stent is a medical device used in the treatment of diseased bodily lumens, such as in the coronary or peripheral vasculature, esophagus, trachea, bronchi colon, biliary tract, urinary tract, prostate, brain, as well as in a variety of other applications in the body. Contemporary endoscopy practitioners increasingly often require visualization of the damaged vessel while delivering the stent. In some cases an endoscope and a stent delivery catheter are separately advanced to the damaged vessel to allow for visualization of the delivery of the stent from the stent delivery catheter. Such a procedure has size limitation, especially for smaller bodily lumens, as both the endoscope and the stent delivery catheter must be navigated to the damaged vessel.
To avoid the need or disadvantage of intraluminally advancing two separate and independent devices, endoscopes and stent delivery systems have been combined. One technique may have a stent disposed within a stent delivery catheter and an endoscope which is slidable within an inner tube of the catheter. For example, U.S. Patent Application Publication No. 2006/0184224 A1 to Angel and U.S. Pat. No. 6,033,413 to Mikus et al. describe stent delivery systems having a catheter holding a stent between two tubes of the catheter and an endoscope being positioned within the inner shaft of the catheter. The combining of a stent delivery catheter and an endoscope in such a manner, however, limits the diameter of the contracted or loaded stent to a diameter larger than that of the endoscope. In other words, the overall profile of the delivery system is constrained by the size of the endoscope.
Another technique used to avoid the need for separately advancing independent endoscopes and stent delivery catheters, is to have a stent constrained within a stent delivery catheter where the stent delivery catheter is slidably disposed within a lumen of the endoscope. For example, U.S. Patent Application Publication Nos. 2002/0143387 A1 to Soetikno et al.; 2004/0098105 A1 to Stinson et al.; 2005/0090889 A1 to Yanuma et al. and 2005/0125050 A1 to Carter et al. and U.S. Pat. No. 6,162,231 Mikus et al.; U.S. Pat. No. 6,093,194 to Mikus et al. and U.S. Pat. No. 6,620,570 to Stinson et al. describe a stent delivery catheter having a stent disposed between two tubes where the catheter is fittable through a working channel of an endoscope. Again, the overall profile of the endoscope is limited to a relatively large size as the endoscope must be sized for accenting the stent delivery catheter.
Other approaches include the endoscopic systems as described in U.S. Pat. No. 6,176,873 to Ouchi and U.S. Pat. No. 6,146,389 to Geitz, and International PCT Patent Application Publication No. WO 2005/122953 A2 to Selden. Ouchi describes an endoscope having a mesh stent disposed within the endoscope. The stent has includes rings or tubes at both ends of the stent where the rings or tubes restrict the diameter of the stent ends. A pusher tube within the endoscope is described as being pushed to engage the ring or tube at the distal end of the stent to radially contract the stent and to urge the contracted stent out from a working channel of the endoscope. Such a system makes stent placement difficult as the stent is pushed away from the distal end of the endoscope. Further, the need of rings or tubes at the ends of the stent which are smaller in diameter than the diameter of the expanded stent, limits the use of such a stent as the smaller ends of the stent will tend to restrict flow through the stent. Geitz describes an endoscope having a distal cap. A stent may be disposed over the distal cap and held there via an overlying sheath. For delivery the sheath is removed to deploy the stent. Selden describes a stent radially compressed against the sidewall of the distal portion of an endoscope. The stent is pushed out of the endoscope by a slidable release disposed within the endoscope that engages over the proximal end of the stent. The stent of Seldon is a highly flared stent with outwardly flared ends. Again the pushing of the stent out of the endoscope is problematic as accurate stent placement is difficult. Further, the device of Seldon is apparently limited to a particular stent design, i.e., a highly flared configuration with only the very terminal end portions of the stent being engageable with the wall to the endoscope such that the longitudinal expanse of the stent does not engage the wall of the endoscope as the stent is being pushed out of the endoscope.
Thus, despite the efforts of the prior art, there is a need for an improved endoscopic stent delivery system. In particular, there is a need for an endoscopic stent delivery system which allows for accurate placement and delivery of the stent and which is not limited or constrained to particular stent designs or sizes as with the prior art devices.